title: Germinal centre B cells: antigen specificity and changes in heavy chain class expression.
abstract: Germinal centres are histologically defined aggregates of blast cells that occur in B-cell areas of lymphoid tissues after antigenic stimulation. They are believed to be associated with the development of B-cell memory and plasma cell (especially secondary, IgG and IgA) responses. Recent studies of murine lymphoid tissues have defined cell-surface markers that distinguish germinal centre B cells from other mature B cells, permitting their identification and characterization in cell suspensions. Here we have used these markers to define and study germinal centre cells in lympho nodes, and have found that they constitute a unique population of B cells which (1) arises in response to antigenic stimulation, (2) contains nearly all of the demonstrably antigen-specific B cells in the stimulated organ, (3) bears surface IgM after primary stimulation and (4) as a population, demonstrates isotype switching to a predominant population, demonstrates isotype switching to a predominant surface IgG phenotype after secondary stimulation with specific surface IgG phenotype after secondary stimulation with specific antigen. These findings demonstrate that germinal centres are a major site of proliferation and differentiation of antigen-specific B cells in vivo, and suggest that the germinal centre microenvironment may have an important role in heavy chain class switching during B-cell responses.
mesh_terms: D000818:Animals; D000916:Antibody Diversity; D000954:Antigens, Surface / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D002462:Cell Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000276:immunology; D007126:Immunoglobulin Allotypes / Q000276:immunology; D007072:Immunoglobulin D / Q000276:immunology; D007143:Immunoglobulin Heavy Chains / Q000276:immunology*; D037102:Lectins / Q000378:metabolism; D008198:Lymph Nodes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D019887:Peanut Agglutinin; D011975:Receptors, Mitogen / Q000378:metabolism; D012397:Rosette Formation
chemical_list: D000954:Antigens, Surface; D007126:Immunoglobulin Allotypes; D007072:Immunoglobulin D; D007143:Immunoglobulin Heavy Chains; D037102:Lectins; D019887:Peanut Agglutinin; D011975:Receptors, Mitogen